As new cases and concerns about seasonal flu and swine flu (H1N1) continue to spread worldwide, two vaccines have recently been made available. Both the nasal spray vaccine and injectable vaccine for seasonal flu have proven effective for specific portions of the population, however distribution is still slow. For the H1N1 (swine flu) virus, The Baltimore Sun reports, availability is still an issue and many areas have not yet received enough doses to meet the demand. While many in the developed world do not yet have access to the H1N1 vaccine, Dr. Bernadine Healy notes that the problem is even greater in the developing world. To help these nations fight the pandemic, the United States has agreed to donate 10 percent of its vaccination supply to the World Health Organization (WHO) – eight other nations will make similar donations.

Inoculating individuals for both viruses is complicated by the time frame in which the vaccinations can occur. If one chooses nasal spray for both seasonal and swine flu, they must wait four weeks between doses, while if one is injected for one virus and uses nasal spray for the other, they can be administered together. Discovery Health reports that doctors recommend annual flu shots to lessen the chances of becoming ill. Individuals as young as six months can be inoculated, according to the Centers for Disease Control and Prevention (CDC) and side effects are reported to be minor. Because the virus used to make the seasonal flu vaccine is dead, it is not possible to contract flu from a flu shot, however one may expect a low-grade fever 8 to 24 hours following injection, a swollen or tender area around the injection site, a slight headache or chills within 24 hours.

The seasonal flu shot is an inactivated vaccine, and contains three influenza viruses – one A(H3N2) virus, one regular seasonal A(H1N1) virus (which differs from the 2009 H1N1 virus), and one B virus. The viruses used change annually based on international surveillance which track infection trends and scientists estimations about which strains will circulate during the year. In contrast to the flu shot, the nasal-spray flu vaccine contains a weakened but still living flu virus, sometimes called LAIV (live attenuated influenza vaccine). These nasal mists are approved for use in healthy individuals ages two to 49 who are not pregnant. In addition to nasal sprays, Discovery Health reports that researchers at Stanford University and the University of Alabama at Birmingham have been working with naked DNA in an effort to develop a vaccine that could be delivered via shampoo or dermal patch.

Three recent large-scale studies, including a study led by Dr. Arnold S. Monto of the University of Michigan, indicate that while the seasonal flu shot is more effective for adults and safe for women who are pregnant, the intranasal vaccine (nasal spray) is more effective at preventing flu in children. These studies showed 35 to 53 percent fewer cases of flu in children who were given the nasal spray vaccine than those who received injected vaccines. The Los Angeles Times reports that injectable vaccines prevent roughly 50 percent more seasonal flu in healthy adults than the nasal spray vaccines.

Due to the relative newness of the H1N1 vaccine, health authorities have implemented a number of tracking measures to ensure its safety. The Associated Press reports that Harvard Medical School scientists are working to link insurance databases covering 50 million people with vaccination registries to allow them to determine if people visit a doctor after being vaccination as well as the reason for the visit. Johns Hopkins University and the CDC are also working to ensure that any side effects are noted and addressed quickly. These efforts include emailing individuals who have been vaccinated recently to see how they are feeling (Johns Hopkins), and preparing take-home cards asking vaccine recipients to report any side effects to the nation’s Vaccine Adverse Event Reporting system (CDC). These measures are being undertaken as in the Internet-age, the Associated Press notes, one person updating their Facebook status to say that they got a flu shot and feel sick could cause a wave of similar reports.